Garmin 'calibration'

[murr_walker]

Hello all,

Got a garmin 510 with speed cadance sensor.....

Done a few rides with mates recently and comparing a garmin 500 to 510 the Mileage & speed have been similar, however tonight been out with same mate and I covered 34.1 miles And he only did 33.1, if anything he cover a few points more in difference where we live. Our ride time was almost the same therefore my average speed was higher.

I recently changed my tyres to 25mm from 23mm but as far as I'm aware the garmin should self calibrate? The difference in circumference is only small anyway...



can anyone explain this or is there some calibration that can be done, or do we just put it down to a gps anomaly?

Thanks

 

[RussellZero]

I think they only calibrate when you tell it to, or add a new bike profile. There should be a menu option in the bike profile to tell it to forget the diameter and recalibrate from GPS.

(Edit). Just looked and it appears it's meant to continuously monitor and recalibrate, so there isn't an option to reset. If it were me I might try setting up a new bike profile anyway and seeing if that works. It may be averaging the calibration over the full history of log data.

 

[Shanks]

I have the 800 bit assume it's the same system. If you use the gps it uses that to measure distance etc and ignores any calibration. If it is using the wheel magnets then it's entirely down to the settings you input when you set up the profile. You can edit these at any time. But tyre pressure and size will have an impact. Pump your tyre up to normal pressure then mark a point on the floor, I do it in line with the valve. Then roll forward and mark again when the valve hits the floor again. Measure the distance and input that as the.profile. Leave the gps on and in my experience it's more accurate. I only turn it off for turbo sessions. Cheers

 

[BSRU]

I stopped using auto-calibration as it can result in different results for the exact same ride.
In my opinion far better to set the wheel circumference manually, Conti actually put this information on the box(for GP4000s and 4 Season tyres at least).

 

[snorri]

. Then roll forward and mark again when the valve hits the floor again.

Sitting on the bike as you roll it forward